Compounds capable of absorbing or emitting light can be used in a variety of optical and electro-optical devices, including photo-absorbing devices (e.g., solar- and photo-sensitive devices), photo-emitting devices, organic light-emitting diodes (OLEDs), and devices capable of photo-absorption and photo-emission. Much research has been devoted to the discovery and optimization of organic and organometallic materials for use in optical and electro-optical devices. Metal complexes can be used for many applications, such as emitters for OLEDs. Despite advances in research devoted to optical and electro-optical materials, many currently available materials exhibit a number of disadvantages, including poor processing ability, inefficient emission or absorption, and insufficient stability.